Two branch-line (BL) couplers based an finite-ground coplanar-waveguide (FG
CPW) structures are proposed. The first one uses the bended structure to re
duce the size of the normal quarter-wavelength two-arm BL coupler. The seco
nd one improves the bandwidth by adding external compensated networks, whic
h are also folded for size reduction. In this study, the performances of th
ese BL couplers are examined, theoretically and experimentally.